selective laser melting

Submitted by nada on Thu, 01/07/2021 - 12:24

Hello,
I am trying to run a simulation where particles released freely from a height of 700 µm, due to gravitational and contact forces, these released powders freely deposited into the box and formed a powder bed. A roller is then applied to spread a 50 µm high layer of metal particles.
Can anyone share a code for that ? With which tutorials I can start or modify it or which command I should use ?
I am actually a total beginner. I would be glad if anyone can help through with the steps involved in the simulation.
thnx.

Forums:

deepakpawar.2310 | Fri, 01/08/2021 - 05:42

I think you need to start with by exploring the different example available in Tutorials folder.
First start with sample preparation (for that you can see the insert_stream example)
Afterwords conveyor example might help you for the rolling mesh movement.

Thanks

Happy learning !

nada | Fri, 01/08/2021 - 15:40

thanks for your reply.I'm going to start with the conveyor script and want to modify it, in my work I'm going to assume that the conveyor is the platform or substrate on which the powder particles are going to be spread layer by layer. So I don't want the particles to go beyond the limits of the conveyor, i.e. do not leave the conveyor, they remain accumulated on the conveyor, are there any commands that I must add or change in the following script ?
thanks,

deepakpawar.2310 | Fri, 01/08/2021 - 20:00

Hi

I guess, you can insert the planes around the conveyor to retain the particles within the conveyor domain.
You can use the piece of snippet to do so. (for example)

fix xplane1 all wall/gran model hertz tangential history primitive type 2 xplane -0.005
fix xplane2 all wall/gran model hertz tangential history primitive type 2 xplane 0.005
fix yplane1 all wall/gran model hertz tangential history primitive type 2 yplane -0.005
fix yplane2 all wall/gran model hertz tangential history primitive type 2 yplane 0.005
fix zplane1 all wall/gran model hertz tangential history primitive type 2 zplane -0.005

Thanks

Happy learning !!

nada | Sat, 01/09/2021 - 12:36

thank you very much for your answer, my problem is how to spread these particles all along the conveyor ie I want to make a thin layer of the particles, 30 micrometer thick I want to spread it using a roller then a laser beam sweeps this layer of particles then a second layer will also be spread with the roller and so on until 7 layers of particles are made. Is there a script to follow or modify or they are the command lines to insert? this is the script i use
#Conveyor
atom_style granular
atom_modify map array
boundary m m m
newton off

communicate single vel yes

units si

region reg block -0.5 0.5 -0.2 0.2 -0.2 0.35 units box
create_box 1 reg

neighbor 0.01 bin
neigh_modify delay 0

#Material properties required for new pair styles

fix m1 all property/global youngsModulus peratomtype 5.e6
fix m2 all property/global poissonsRatio peratomtype 0.45
fix m3 all property/global coefficientRestitution peratomtypepair 1 0.3
fix m4 all property/global coefficientFriction peratomtypepair 1 0.5

#New pair style
pair_style gran model hertz tangential history #Hertzian without cohesion
pair_coeff * *

timestep 0.00001

fix gravi all gravity 9.81 vector 0.0 0.0 -1.0

#granular walls
fix cv all mesh/surface file meshes/conveyor.stl type 1 surface_vel -4.5 0. 0.
fix bx all mesh/surface file meshes/box.stl type 1
fix inface all mesh/surface file meshes/insertion_face.stl type 1
fix xplane1 all wall/gran model hertz tangential history primitive type 1 xplane -0.005
fix xplane2 all wall/gran model hertz tangential history primitive type 1 xplane 0.005
fix yplane1 all wall/gran model hertz tangential history primitive type 1 yplane -0.005
fix yplane2 all wall/gran model hertz tangential history primitive type 1 yplane 0.005
fix zplane1 all wall/gran model hertz tangential history primitive type 1 zplane -0.005
fix wall all wall/gran model hertz tangential history mesh n_meshes 2 meshes bx cv

#distributions for insertion
fix pts1 all particletemplate/sphere 15485863 atom_type 1 density constant 2500 radius constant 0.015
fix pts2 all particletemplate/sphere 15485867 atom_type 1 density constant 2500 radius constant 0.025
fix pdd1 all particledistribution/discrete 32452843 2 pts1 0.3 pts2 0.7

#region for insertion
group nve_group region reg
region bc block 0.3 0.5 -0.2 0.2 0.1 0.2 units box

#deprecated pour command
#fix ins nve_group pour/dev mass 30. 1 distributiontemplate pdd1 vol 0.25 200 massflowrate 30. vel uniform 0. 0. 0. 0. 0.0 region bc

#particle insertion
fix ins nve_group insert/stream seed 32452867 distributiontemplate pdd1 &
maxattempt 100 mass 30. massrate 30. overlapcheck yes vel constant 0. 0. -1.0&
insertion_face inface extrude_length 0.1

#apply nve integration to all particles that are inserted as single particles
fix integr nve_group nve/sphere

#output settings, include total thermal energy
fix ts all check/timestep/gran 1000 0.1 0.1
compute rke all erotate/sphere
thermo_style custom step atoms ke c_rke f_ts[1] f_ts[2] vol
thermo 1000
thermo_modify lost ignore norm no

#insert the first particles so that dump is not empty
run 1
dump dmp all custom/vtk 400 post/conveyor_*.vtk id type type x y z ix iy iz vx vy vz fx fy fz omegax omegay omegaz radius

#insert particles
run 140000 upto
unfix ins

pawandubey | Wed, 03/10/2021 - 11:54

If you were able to model, please help me. I am also working on SLM and have just started with open source solvers. I looked for particle bed creation and melting in liggghts and openfoam but could not find any useful link.